Display module and manufacturing method thereof

ABSTRACT

A display module and a manufacturing method thereof are provided. The manufacturing method may include forming an epitaxial film comprising a light emitting layer, a first type semiconductor layer, and a second type semiconductor layer, attaching the epitaxial film to an intermediate substrate comprising a conductive material, patterning the epitaxial film to form a light emitting diode (LED) and coupling the LED to a driving circuit layer through the conductive material.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority under 35 U.S.C. § 119to Korean Patent Application No. 10-2019-0128028, filed on Oct. 15, 2019and Korean Patent Application No. 10-2019-0152622, filed on Nov. 25,2019, in the Korean Intellectual Property Office, the disclosures ofwhich are herein incorporated by reference in their entireties.

BACKGROUND Field

Apparatuses and methods consistent with the disclosure relate to adisplay module and a manufacturing method thereof, and moreparticularly, to a display module for a micro light emitting diode (LED)and a manufacturing method thereof.

Description of the Related Art

A light emitting diode (LED) is a semiconductor element that emits lightwhen a voltage is applied thereto, and is widely used as a light sourcefor display devices for displaying images as well as general lightingdevices.

Recently, a display device, a display panel, a display module, etc.,using a micro LED (μ-LED), or a micro light emitting diode as a lightsource in unit of pixel or sub-pixel has been developed. Here, the microLED may refer to a semiconductor light emitting element having a width,a length, and a height of 1 to 100 micrometers (μm), respectively.

A micro LED display module (or a display panel) using the micro LED asthe light source provides better contrast, response time, and energyefficiency, compared to a liquid crystal display (LCD) that requires aseparate backlight unit. Moreover, the micro LED display module usingthe micro LED has advantages such as less burn-in of a screen, longerlife, higher luminance efficiency, and brighter brightness than anorganic LED (OLED) that uses an inorganic material.

In general, in the case of a display module using the micro LED as thelight source, the micro LED is used as a flip-chip structure, and theflip-chip structure requires bumps and pads for contacting the micro LEDwith a thin film transistor (TFT) circuit board. The bumps serve toalign the heights of the positive electrodes (e.g., apositive-contact-metal and a negative-contact-metal) of the flip-chip,and serve to facilitate a connection of the contact-metals of theflip-chip with external electrodes (e.g., contact-metals of a circuitboard). For such a reason, the bumps require a good adhesion between afinal metal layer of a chip-pad and a metal layer of the circuit boardand an electrical resistance to be low. In general, Au-Bump plating ismainly used as a material for the bumps. As an example, when the microLED is transferred to a TFT circuit board through a stamp transferprocess, an anisotropic conductive film (ACF) is used. Here, the ACFserves as a binder, and Ni particles contained in the ACF are each usedfor the purpose of facilitating the connection of the contact metals ofthe micro LED chip with the contact-metals of the TFT circuit board.

However, as a chip size of the micro LED is miniaturized, a gap betweenthe positive electrodes (or the positive electrodes of the TFTsubstrate) becomes too narrow, and there is a problem in that a shortoccurs as the Ni particles invade a region of the positive electrodes.

In addition, bonding through the ACF or bump soldering requires a heattreatment process, and problems such as an occurrence of cracks andmisalignment of micro LEDs occur in the bumps according to the heattreatment process. Due to the problems described above, the micro LEDmay not emit light properly, resulting in defective pixels, which inturn causes a decrease in yield for production of the display module.

SUMMARY

Embodiments of the disclosure overcome the above disadvantages and otherdisadvantages not described above. Also, the disclosure is not requiredto overcome the disadvantages described above, and an embodiment of thedisclosure may not overcome any of the problems described above.

According to an aspect of the disclosure, there is provided a method ofmanufacturing a display module, the method comprising: forming anepitaxial film comprising a light emitting layer, a first typesemiconductor layer, and a second type semiconductor layer; attachingthe epitaxial film onto an intermediate substrate comprising aconductive material; patterning the epitaxial film to form a lightemitting diode (LED); and electrically connecting the LED to a drivingcircuit layer through the conductive material.

The connecting the LED to the driving circuit layer may comprise:attaching the intermediate substrate onto the driving circuit layerformed on a substrate to electrically connect the first typesemiconductor layer of the LED to the driving circuit layer through theconductive material and to electrically connect the second typesemiconductor layer of the LED to the driving circuit layer through theconductive material.

The LED may have a vertical structure, and the conductive material maycomprise at least one of carbon nano tube (CNT), graphene, or metal nanowire.

The driving circuit layer may comprise a pixel circuit, and a firstelectrode and a second electrode coupled to the pixel circuit toelectrically connect the first electrode and the second electrode to thepixel circuit.

The method may further comprise forming a passivation element on asidewall of the LED.

The connecting the second type semiconductor layer of the LED to thedriving circuit layer may comprise forming a transparent electrode alongthe passivation element; and electrically connecting the second typesemiconductor layer of the LED to the second electrode of the drivingcircuit layer through the transparent electrode and the conductivematerial.

The method may further comprise forming a black matrix on theintermediate substrate in a region between the LED and another LED.

The intermediate substrate may further comprise an adhesive material,and wherein the intermediate substrate is attached onto the drivingcircuit layer through the adhesive material to electrically connect thefirst type semiconductor layer of the LED to the first electrode of thedriving circuit layer through the conductive material.

The adhesive material may comprise at least one of epoxy, polyimide, orphenol.

The method may further comprise forming a reflective electrode on alower portion of the first type semiconductor layer or an upper portionof the second type semiconductor layer.

According to another aspect of the disclosure, there is provided adisplay module comprising: a substrate; a driving circuit layer providedon the substrate, the driving circuit layer comprising a pixel circuitand a plurality of electrodes configured to be electrically connected tothe pixel circuit, wherein the plurality of electrodes comprise a firstelectrode and a second electrode; an intermediate substrate comprising afirst conductive portion, a second conductive portion and an adhesiveportion provided in different regions, respectively, the intermediatesubstrate being attached onto the driving circuit layer through theadhesive portion; and a light emitting diode (LED) provided on theintermediate substrate, wherein the plurality of electrodes include afirst electrode and a second electrode, the LED comprises a lightemitting layer, and a first type semiconductor layer and a second typesemiconductor layer provided on upper and lower portions of the lightemitting layer, respectively, the first type semiconductor layer isconfigured to electrically connect to the first electrode through thefirst conductive portion, and the second type semiconductor layer isconfigured to electrically connect to the second electrode through thesecond conductive portion.

The LED may have a vertical structure.

The display module may further comprise a passivation element providedon a sidewall of the LED.

The LED may further comprise a transparent electrode provided along thepassivation element, and the second type semiconductor layer isconfigured to be electrically connected to the second electrode throughthe transparent electrode.

The display module may further comprise a black matrix provided on theintermediate substrate in a region between the LED and another LED.

The transparent electrode may be a same material as the first conductiveportion and the second conductive portion of the intermediate substrate.

Each of the first conductive portion and the second conductive portionmay comprise at least one of carbon nano tube (CNT), graphene, or metalnano wire.

The adhesive portion may comprise at least one of epoxy, polyimide, orphenol.

The display module may further comprise a reflective electrode providedon a lower portion of the first type semiconductor layer or an upperportion of the second type semiconductor layer.

According to another aspect of the disclosure, there is provided adisplay device comprising: a substrate; a driving circuit layer providedon the substrate, the driving circuit layer comprising a pixel circuit,a first electrode and a second electrode; an intermediate substratecomprising a first portion and a second portion having a conductivematerial, and a third portion having an adhesive material, theintermediate substrate being attached to the driving circuit layerthrough the adhesive material in the third portion; a light emittingdiode (LED) provided on the intermediate substrate and having a lightemitting layer, and a first type semiconductor layer and a second typesemiconductor layer, wherein the first type semiconductor layer iselectrically connectable to the first electrode through the conductivematerial in the first portion, and wherein the second type semiconductorlayer is electrically connectable to the second electrode through theconductive material in the second portion.

The display module may further comprise a first path configured toelectrically connect the first electrode to the first type semiconductorlayer of the LED through the conductive material in the first portion ofthe intermediate substrate.

The display module may further comprise a second path to electricallyconnect the second electrode to the second type semiconductor layer ofthe LED through the conductive material in the second portion of theintermediate substrate.

According to another aspect of the disclosure, there is provided amethod of forming a display device comprising: forming an epitaxial filmcomprising a light emitting layer, a first type semiconductor layer, anda second type semiconductor layer; forming an intermediate substrateincluding a first portion and a second portion having a conductivematerial, and a third portion having an adhesive material; attaching theepitaxial film to the intermediate substrate through the adhesivematerial in the third portion of the intermediate substrate; patterningthe epitaxial film to form a light emitting diode (LED); and attachingthe intermediate substrate to a driving circuit layer through theadhesive material in the third portion, the driving circuit layerincluding a pixel circuit, a first electrode and a second electrode.

The method may further comprise forming a first path to electricallyconnect the first electrode to the first type semiconductor layer of theLED through the conductive material in the first portion of theintermediate substrate.

The method may further comprise forming a second path to electricallyconnect the second electrode to the second type semiconductor layer ofthe LED through the conductive material in the second portion of theintermediate substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects of the disclosure will be more apparentby describing certain embodiments of the disclosure with reference tothe accompanying drawings, in which:

FIG. 1 is a view for describing a display module according to anembodiment of the disclosure;

FIG. 2 is a view for describing a display module according to anembodiment of the disclosure;

FIG. 3 is a view for describing in more detail a display moduleaccording to an embodiment of the disclosure;

FIG. 4A is a view for describing in more detail a display moduleaccording to an embodiment of the disclosure;

FIG. 4B is a view for describing in more detail a display moduleaccording to an embodiment of the disclosure;

FIG. 5 is a flowchart for describing a method for manufacturing adisplay module according to an embodiment of the disclosure;

FIG. 6A is a view for describing an operation of forming an epitaxialfilm according to an embodiment of the disclosure;

FIG. 6B is a view for describing the operation of forming the epitaxialfilm according to an embodiment of the disclosure;

FIG. 7A is a view for describing an operation of forming an epitaxialfilm according to an embodiment of the disclosure;

FIG. 7B is a view for describing an operation of forming an epitaxialfilm according to an embodiment of the disclosure;

FIG. 8A is a view for describing an operation of forming an intermediatesubstrate according to an embodiment of the disclosure;

FIG. 8B is a view for describing an operation of forming an intermediatesubstrate according to an embodiment of the disclosure;

FIG. 8C is a view for describing an operation of forming an intermediatesubstrate according to an embodiment of the disclosure;

FIG. 9A is a view for describing an operation of bonding an epitaxialfilm onto an intermediate substrate according to an embodiment of thedisclosure;

FIG. 9B is a view for describing an operation of bonding an epitaxialfilm onto an intermediate substrate according to an embodiment of thedisclosure;

FIG. 9C is a view for describing an operation of bonding an epitaxialfilm onto an intermediate substrate according to an embodiment of thedisclosure;

FIG. 9D is a view for describing an operation of bonding an epitaxialfilm onto an intermediate substrate according to an embodiment of thedisclosure;

FIG. 10A is a view for describing a patterning operation according to anembodiment of the disclosure;

FIG. 10B is a view for describing a patterning operation according to anembodiment of the disclosure;

FIG. 10C is a view for describing a patterning operation according to anembodiment of the disclosure;

FIG. 10D is a view for describing a patterning operation according to anembodiment of the disclosure;

FIG. 10E is a view for describing a patterning operation according to anembodiment of the disclosure;

FIG. 10F is a view for describing a structure of a display moduleaccording to a patterning method according to an embodiment of thedisclosure;

FIG. 11A is a view for describing an operation of forming a passivationelement according to an embodiment of the disclosure;

FIG. 11B is a view for describing an operation of forming a passivationelement according to an embodiment of the disclosure;

FIG. 11C is a view for describing an operation of forming a passivationelement according to an embodiment of the disclosure;

FIG. 12A is a view for describing an inspection method according to anembodiment of the disclosure;

FIG. 12B is a view for describing an inspection method according to anembodiment of the disclosure;

FIG. 13A is a view for describing an operation of bonding anintermediate substrate onto a substrate 10 according to an embodiment ofthe disclosure;

FIG. 13B is a view for describing an operation of bonding anintermediate substrate onto a substrate 10 according to an embodiment ofthe disclosure;

FIG. 13C is a view for describing an operation of bonding anintermediate substrate onto a substrate 10 according to an embodiment ofthe disclosure;

FIG. 13D is a view for describing an operation of bonding anintermediate substrate onto a driving circuit layer according to anembodiment of the disclosure.

FIG. 13E is a view for describing an operation of bonding anintermediate substrate onto a driving circuit layer according to anembodiment of the disclosure.

FIG. 14A is a view for describing an operation of forming electrodesaccording to an embodiment of the disclosure;

FIG. 14B is a view for describing an operation of forming electrodesaccording to an embodiment of the disclosure;

FIG. 14C is a view for describing an operation of forming electrodesaccording to an embodiment of the disclosure;

FIG. 14D is a view for describing an operation of forming electrodesaccording to an embodiment of the disclosure; and

FIG. 15 is a view for describing an operation of forming black matricesaccording to an embodiment of the disclosure.

DETAILED DESCRIPTION

An object of the disclosure is to provide a display module and amanufacturing method thereof that solve various problems such as adefect rate, a non-illumination rate, and a reduction in yield of therelated art μ-LED process while alleviating the limitations of therelated art μ-LED structure.

In describing the disclosure, a detailed description for the knownfunctions or configurations related to the disclosure, which mayunnecessarily obscure the gist of the disclosure, may be omitted. Inaddition, the following embodiments may be modified to several differentforms, and the scope and spirit of the disclosure are not limited to thefollowing embodiments. Rather, these embodiments make the disclosurethorough and complete, and are provided in order to completely transferthe technical spirit of the disclosure to those skilled in the art.

It is to be understood that technologies mentioned in the disclosure arenot limited to specific embodiments, but include all modifications,equivalents, and/or substitutions according to embodiments of thedisclosure. Throughout the accompanying drawings, similar componentswill be denoted by similar reference numerals.

Expressions “first”, “second”, and the like, used in the disclosure mayindicate various components regardless of a sequence and/or importanceof the components, will be used only in order to distinguish onecomponent from the other components, and do not limit the correspondingcomponents.

In the disclosure, an expression “A or B”, “at least one of A and/or B”,“one or more of A and/or B”, or the like, may include all possiblecombinations of items listed together. For example, “A or B”, “at leastone of A and B”, or “at least one of A or B” may indicate all of 1) acase in which at least one A is included, 2) a case in which at leastone B is included, or 3) a case in which both of at least one A and atleast one B are included.

In the disclosure, the singular expression includes the pluralexpression unless the context clearly indicates otherwise. It should befurther understood that the term “include” or “constituted” used in theapplication specifies the presence of features, numerals, steps,operations, components, parts mentioned in the specification, orcombinations thereof, but do not preclude the presence or addition ofone or more other features, numerals, steps, operations, components,parts, or combinations thereof.

When it is mentioned that any component (for example, a first component)is (operatively or communicatively) connected with/to or is connected toanother component (for example, a second component), it is to beunderstood that any component is directly connected with/to anothercomponent or may be connected with/to another component through theother component (for example, a third component). On the other hand,when it is mentioned that any component (for example, a first component)is “directly connected with/to” or “directly connected to” to anothercomponent (for example, a second component), it is to be understood thatthe other component (for example, a third component) is not presentbetween any component and another component.

An expression “configured (or set) to” used in the disclosure may bereplaced by an expression “suitable for”, “having the capacity to”,“designed to”, “adapted to”, “made to”, or “capable of” depending on asituation. A term “configured (or set) to” may not necessarily mean only“specifically designed to” in hardware. Instead, in any context, anexpression “a device configured to” may mean that the device is “capableof” together with other devices or components. For example, a “processorconfigured (or set) to perform A, B, and C” may mean a dedicatedprocessor (for example, an embedded processor) for performing thecorresponding operations or a generic-purpose processor (for example, acentral processing unit (CPU) or an application processor) that mayperform the corresponding operations by executing one or more softwareprograms stored in a memory device.

Hereinafter, embodiments of the disclosure will be described in detailwith reference to the accompanying drawings so that those skilled in theart to which the disclosure pertains may easily practice the disclosure.

FIG. 1 is a view for describing a display module according to anembodiment of the disclosure.

Referring to FIG. 1, a display module 1 may include a plurality ofpixels 100-1, 100-2, . . . , 100-n (n is a natural number). In thiscase, the display module 1 may visually display an image (e.g., photo,video, and the like) or information (e.g., letters, numbers, symbols,and the like) through the plurality of pixels 100-1, 100-2, . . . ,100-n.

Here, each of the plurality of pixels 100-1, 100-2, . . . , 100-n may bea minimum unit constituting a screen (region) in which the image or theinformation is displayed on the display module 1, and may appear as apoint having independent color or brightness.

Meanwhile, because the plurality of pixels 100-1, 100-2, . . . , 100-nhave different positions from each other, but have the same structureand function as each other, a description of one pixel 100-1 may beapplied to the other pixel 100-2, . . . , 100-n in the same way unlessotherwise specified. Hereinafter, the pixel 100-1 will be described forconvenience of description.

The pixel 100-1 may be formed of a combination of a plurality ofsub-pixels (e.g., red, green, blue sub-pixels, and the like). That is,one pixel 100-1 may be configured by a combination of colors of aplurality of sub-pixels positioned in regions adjacent to each other.According to an embodiment, the pixel 100-1 or the sub-pixel may beimplemented as a semiconductor element (e.g., a light emitting diode(LED) 50 (see FIG. 2)) that emits light. As such, the plurality ofpixels 100-1, 100-2, . . . , 100-n may be implemented as a plurality ofsemiconductor elements (e.g., a plurality of LEDs 50). More specificdetails will be described later.

The plurality of pixels 100-1, 100-2, . . . 100-n may be arranged spacedapart from each other at intervals therebetween. According to anembodiment, the intervals are predetermined. According to an embodiment,the intervals are regular intervals. That is, the plurality of pixels100-1 and 100-2 may be arranged in a matrix type (e.g., M×N, where M andN are each a natural number).

Meanwhile, the display module 1 may be implemented as a display deviceby itself (i.e., a single display module 1), or a plurality of displaymodules may be combined to be implemented as a single display device.For example, the plurality of display modules may be tiled in a matrixtype (e.g., Q×W, where Q and W are each a natural number) to configure asingle display device.

The display device may refer to a device capable of visually displayingan image by processing an image signal received from an external deviceor an image signal stored in a storage through an image processor, orvisually displaying information processed by a processor. According toan embodiment, the processor may be a hardware processor. According toan embodiment, the display device may be implemented in various formssuch as a TV, a monitor, a portable multimedia device, a portablecommunication device, a smart phone, a smart glass, a smart window, asmart watch, a head mounted display (HMD), a wearable device, a portabledevice, a handheld device, a signage, an electronic scoreboard, abillboard, a cinema screen, a video wall, and the form thereof is notlimited.

That is, the display module 1 according to an embodiment of thedisclosure may be installed and applied to a wearable device, a portabledevice, a handheld device, and an electronic product (i.e., a smalldisplay device) or an electronic device that requires various displaysin a single unit, and the display module 1 may be applied to anelectronic product (i.e., a large display device) or an electronicdevice such as monitor, a high-definition TV, a signage (or a digitalsignage), and an electronic scoreboard through an assembly arrangementof a matrix type in a plurality of units. Further, the display module 1according to an embodiment of the disclosure may also be applied to atransparent display device such as a smart window or a smart glass.

Hereinafter, the display module 1 according to an embodiment of thedisclosure will be described in more detail with reference to theaccompanying drawings.

FIGS. 2, 3, 4A and 4B are views for describing in more detail thedisplay module 1 according to an embodiment of the disclosure. FIGS. 2,3, 4A and 4B illustrate cross-sectional views of the display module 1for one unit LED 50.

Referring to FIG. 2, the display module 1 according to an embodiment ofthe disclosure may include a substrate 10, a driving circuit layer 20,an intermediate substrate 40, and an LED 50.

The substrate 10 may support and protect various electronic elementssuch as the driving circuit layer 20 and the LED 50. In addition, thesubstrate 10 may have transparent properties, rigid properties orflexible properties. According to an embodiment, the substrate 10 may beimplemented with various materials such as glass, polyimide (PI),polyethylene terephthalate (PET), polyethylene naphthalate (PEN),polyvinyl chloride (PVC), and poly methyl methacrylate (PMMA).

The driving circuit layer 20 may be provided on the substrate 10. Thedriving circuit layer 20 may be electrically connected to the LED 50 andmay allow the LED to emit light 50 by applying power (e.g., voltage orcurrent) to the LED 50. That is, the driving circuit layer 20 maycontrol the power to drive the LED 50. Here, the power may be applied invarious forms such as an alternating current (AC), a direct current(DC), a square wave, and a triangular wave. Meanwhile, the drivingcircuit layer 20 may be configured as various circuits according to amethod (e.g., DC driving, AC driving, pulse width modulation (PWM)driving, or the like) of controlling the driving of the LED 50.

As an example, referring to FIG. 3, the driving circuit layer 20 mayinclude a pixel circuit 21 and a plurality of electrodes 28 and 29.

The pixel circuit 21 may drive the LED 50 so that the LED 50 emitslight. According to an embodiment, the LED 50 is mounted (or bonded) onthe pixel circuit 21, so that the LED 50 and the pixel circuit 21 may beelectrically connected to each other. At this time, the LED 50 mayconstitute sub-pixels (e.g., red, green, and blue) of the display module1. That is, the pixel circuit 21 may be formed for the LED 50corresponding to one of the red (R) sub-pixel, the green (G) sub-pixel,and the blue (B) sub-pixel.

According to an embodiment, the pixel circuit 21 may include a switchingelement, a capacitor, a metal wire, an insulator, and the like. Here,the switching device may be implemented as an amorphous silicon (A-Si)based TFT, a low-temperature polycrystalline silicon (LTPS) based TFT,or the like. The TFT (or backplane) may include a gate, a source, and adrain, and when a voltage is applied to the gate, a channel is formed,and a current flows from the source to the drain, which causes a current(or voltage) to be transmitted to the LED 50 so that the LED 50connected to the pixel circuit 21 emits light. Here, the TFT is notlimited to a specific structure or type. That is, the TFT may beimplemented as a low-temperature polycrystalline silicon (LTPS) TFT, anoxide TFT, a poly silicon TFT, an amorphous silicon (a-silicon) TFT, anorganic TFT, a graphene TFT, or the like, and may be implemented invarious types such as a P type (or N-type) MOSFET formed in a Si waferCMOS process.

The plurality of electrodes 28 and 29 of the driving circuit layer 20may include a first electrode 28 and a second electrode 29. Here, thefirst electrode 28 may be one of an anode and a cathode, and the secondelectrode 29 may be one of the anode and the cathode that is differentfrom the first electrode 28. For instance, according to an embodiment,the first electrode 28 may be an anode and the second electrode 29 maybe a cathode. According to another embodiment, the first electrode 28may be a cathode and the second electrode 29 may be ab anode.

The plurality of electrodes 28 and 29 of the driving circuit layer 20may be electrically connected to the pixel circuit 21. That is, thefirst electrode 28 and the second electrode 29 may be electricallyconnected to the pixel circuit 21 by ohmic contact with the pixelcircuit 21. In this case, the pixel circuit 21 may be electricallyconnected to the LED 50 through the first electrode 28 and the secondelectrode 29. For example, the pixel circuit 21 may be electricallyconnected to a first type semiconductor layer 51 of the LED 50 throughthe first electrode 28, and a first conductive portion 48 and 58 of theintermediate substrate 40. The pixel circuit 21 may be electricallyconnected to a second type semiconductor layer 55 of the LED 50 throughthe second electrode 29, a second conductive portion 49 of theintermediate substrate 40, and an upper electrode 59 of the LED 50.

Each of the plurality of electrodes 28 and 29 of the driving circuitlayer 20 may be implemented with a material having various propertiessuch as transparent properties and flexible properties, in addition toelectrical conductivity. For example, each of the plurality ofelectrodes 28 and 29 may be implemented in the form comprising at leastone of Al, Ti, Ni, Pd, Ag, Au, Au—Ge, indium-tin-oxide (ITO), or ZnO.

The intermediate substrate 40 may be attached on the driving circuitlayer 20. In addition, in this case, a lower portion of the LED 50 maybe bonded (or attached) onto an upper portion of the intermediatesubstrate 40, and an upper portion of the driving circuit layer 20 maybe bonded (or attached) onto a lower portion of the intermediatesubstrate 40. That is, the intermediate substrate 40 may be attachedonto the driving circuit layer 20 in a state in which a plurality ofLEDs 50 are bonded onto the intermediate substrate 40. Accordingly, thedriving circuit layer 20 may be electrically connected to the LED 50through the intermediate substrate 40.

Here, the intermediate substrate 40 may be a prepreg (preimpregnatedmaterial). At this time, the prepreg may be a generic term for amaterial mixed-molded by impregnating a resin with a fiber material(e.g., fiber, fabric). Because the prepreg may precisely control a ratioof the resin to the fiber material (e.g., mainly carbon fiber material)and may increase a volume ratio of the fiber material, the prepreg hasan advantage of improving various properties such as strength,stiffness, corrosion resistance, fatigue life, wear resistance, impactresistance, weight reduction, reliability, and elasticity compared toother materials. In addition, when the prepreg is formed in the form ofa sheet, there is an advantage that the prepreg may be easily cut andused to a desired size.

As an example, referring to FIG. 3, the intermediate substrate 40 (e.g.,prepreg) may include an adhesive portion 43, a first conductive portion48 and 58, and a second conductive portion 49. The intermediatesubstrate 40 may be attached onto the driving circuit layer 20 throughthe adhesive portion 43. Specifically, the adhesive portion 43 may bemade of a resin or the like, and may have a tack, and the intermediatesubstrate 40 may be attached onto the driving circuit layer 20 by thetack of the adhesive portion 43.

Here, the adhesive portion 43 (or the adhesive material) may include atleast one of epoxy, polyimide, or phenol. Accordingly, a surface of theintermediate substrate (e.g., prepreg) 40 may have the tack.

The driving circuit layer 20 may be electrically connected to theplurality of LEDs 50 through the first conductive portion 48 and 58, andthe second conductive portion 49. At this time, the first conductiveportion 48 and 58 (or first conductive material), and the secondconductive portion 49 (or second conductive material) may be implementedwith a fiber material having electrical conductivity of a predeterminedvalue or more. In addition, in this case, the plurality of LEDs 50 maybe attached onto the intermediate substrate 40 by the first conductiveportion 48 and 58. Specifically, the plurality of LEDs 50 may beattached onto the intermediate substrate 40 by the van der Waals forceof the first conductive portion 48 and 58. At this time, the van derWaals force is a force acting on neutral molecules, and the closer thedistance between the molecules (between the molecules of the LED 50 andthe first conductive portion 48 and 58) is, the stronger the strength ofthe force may be.

According to an embodiment, each of the first and second conductiveportions 48, 49, and 58 may include at least one of carbon nanotube(CNT), graphene, or metal nano wire.

Here, the CNT may refer to an allotrope of carbon in which carbon atomshave a cylindrical or spiral structure. The CNT may have differentoptical transparency and electrical properties (e.g., electricalconductivity, electrical resistance, and the like) according to astructure of CNT (e.g., single wall CNT (SW-CNT), multi wall CNT(MW-CNT), and the like), a diameter of CNT, a molecular length of CNT, aconcentration (or density) of CNT, and a density of hybrid material(e.g., Ag nano wire, TiOx, and the like). Accordingly, the CNT may beused as a black matrix with high resistance, or may also be used as atransparent electrode with high electrical conductivity.

The graphene may refer to an allotrope of carbon in which carbon atomsare connected in a hexagonal honeycomb shape to form a two-dimensionalplanar structure. The graphene may be classified into single-layergraphene or multi-layer graphene according to the number of layers, andoptical transparency and electrical properties may vary depending on thenumber of layers of graphene.

The metal nano wire may refer to a wire structure having a size innanometers. The metal nano wire is in the form of a wire having adiameter between several nanometers and hundreds of nanometers, and mayinclude at least one material among Ag, TiOx, Ni, Pt, Au, Si, InP, GaN,or ZnO.

Meanwhile, the composition or structure of the above-describedintermediate substrate 40 (e.g., prepreg) is only an example, and may bevariously modified and carried out.

The LED 50 may be provided on the intermediate substrate 40. In thiscase, each of the plurality of LEDs 50 may be electrically connected tothe driving circuit layer 20 through the intermediate substrate 40, andmay emit light according to the power applied from the driving circuitlayer 20.

Here, the LED 50 may refer to a semiconductor light emitting element.For example, the LED 50 may be implemented as an inorganicsemiconductor-based micro-LED element or mini-LED device. Here, themicro-LED may refer to a semiconductor light emitting element having awidth, a length, and a height of 1 to 100 micrometers (μm),respectively, and the mini-LED may refer to a semiconductor lightemitting element having a width, a length, and a height of 100 to 200micrometers (μm), respectively. However, this is only an example, and aslong as it is a light-emitting element that meets the object of thedisclosure, the type thereof is not particularly limited.

As an example, referring to FIG. 3, each of the plurality of LEDs 50 mayinclude a first type semiconductor layer 51, a second type semiconductorlayer 55, and a light emitting layer 53.

The first type semiconductor layer 51 may be one of an n-typesemiconductor and a p-type semiconductor, and the second typesemiconductor layer 55 may be one different from the first typesemiconductor layer 51 of the n-type semiconductor and the p-typesemiconductor.

Here, the n-type semiconductor may refer to a semiconductor in whichfree electrons are used as carriers for transferring charges, and thep-type semiconductor may refer to a semiconductor in which holes areused as carriers for transferring charge. According to an embodiment,the n-type semiconductor and the p-type semiconductor may be implementedas compound semiconductors such as group III-V and group II-VI. Inparticular, the n-type semiconductor and the p-type semiconductor may beimplemented as a nitride semiconductor layer. For example, each of then-type semiconductor and the p-type semiconductor may be n-GaN andp-GaN. However, the n-type semiconductor and the p-type semiconductoraccording to the disclosure are not limited thereto, and may be made ofvarious materials according to various characteristics required for thedisplay module 1.

The first type semiconductor layer 51 and the second type semiconductorlayer 55 may be provided on each of upper and lower portions of thelight emitting layer 53. For example, the first type semiconductor layer51 may be provided on the lower portion of the light emitting layer 53,and the second type semiconductor layer 55 may be provided on the upperportion of the light emitting layer 53.

In the first type semiconductor layer 51, the intermediate substrate 40may be bonded onto the driving circuit layer 20. That is, the first typesemiconductor layer 51 may be electrically connected to the firstelectrode 28 of the driving circuit layer 20 through the firstconductive portion 48 and 58 of the intermediate substrate 40, as theintermediate substrate 40 is attached to the driving circuit layer 20.

Specifically, the lower portion of the LED 50, that is, the first typesemiconductor layer 51 may make ohmic contact with the first conductiveportion 48 and 58 of the intermediate substrate 40. That is, the firsttype semiconductor layer 51 may be electrically connected to the drivingcircuit layer 20 through the first conductive portion 48 and 58 of theintermediate substrate 40. That is, the first conductive portion 48 and58 of the intermediate substrate 40 may have a function of electricalconnection with the lower electrode of the LED and the driving circuitlayer 20.

The second type semiconductor layer 55 may be electrically connected tothe second electrode 29 of the driving circuit layer 20 after theintermediate substrate 40 is attached to the driving circuit layer 20.The method of electrical connecting may be different according to thestructure of the LED 50. For instance the method of electricalconnecting may be a vertical structure, a flip-chip structure, and thelike, according to the structure of the LED 50.

As an example, in the case of the vertical structure, each of theplurality of LEDs 50 may further include an upper electrode 59. At thistime, the upper electrode 59 may function as an electrode (or pad) andwiring.

Here, the upper electrode 59 may be provided on the second typesemiconductor layer 55 after the intermediate substrate 40 is attachedto the driving circuit layer 20. At this time, the upper electrode 59may be provided along an upper portion of the second type semiconductorlayer 55 and a side surface of the LED 50.

In this case, the second type semiconductor layer 55 may be electricallyconnected to the driving circuit layer 20 through the upper electrodes59 of the plurality of LEDs 50. For example, the second typesemiconductor layer 55 may be electrically connected to the secondelectrode 29 of the driving circuit layer 20 through the upper electrode59 and the second conductive portion 49 of the intermediate substrate40. That is, the upper electrode 59 may have a function of electricalconnection between the second type semiconductor layer 55 of the LED 50and the second electrode 29 of the driving circuit layer 20.

The light emitting layer 53 may be provided between the first typesemiconductor layer 51 and the second type semiconductor layer 55 by asemiconductor j unction.

Specifically, the light emitting layer 53 may be provided in asingle-quantum well structure (SQW), a multi-quantum well structure(MQW), or a quantum dot (QD) structure at an interface between then-type semiconductor and the p-type semiconductor by junction of then-type semiconductor and the p-type semiconductor. Here, when the lightemitting layer 53 is formed in the multi-quantum well structure, a welllayer/barrier layer of the light emitting layer 53 may be formed in astructure such as InGaN/GaN, InGaN/InGaN, GaAs(InGaAs)/AlGaAs, but thedisclosure is not limited to such a structure. In addition, the numberof quantum wells included in the light emitting layer 53 is also notlimited to a specific number.

In this case, when a current is applied to the first type semiconductorlayer 51 and the second type semiconductor layer 55 in a forward bias(e.g., in the case of a p-n junction connecting a cathode to the n-typesemiconductor and an anode to the p-type semiconductor), the lightemitting layer 53 may generate excitons as electrons of the n-typesemiconductor layer and holes of the p-type semiconductor layerrecombine in the light emitting layer (e.g., quantum well layer), andmay emit light because an energy state of the excitons is shifted. Atthis time, a wavelength of the emitted light may correspond to an energybandgap of the light emitting layer 53, and the energy band gap may bedetermined by its structure, such as the composition and film thicknessof a semiconductor forming the quantum well (QW) layer.

Meanwhile, the first type semiconductor layer 51 or the second typesemiconductor layer 55 according to the disclosure may further includevarious semiconductor layers.

As an example, the first type semiconductor layer 51 may further includea semiconductor layer (a p+ type or n+ type semiconductor layer) dopedwith a stronger dopant concentration than a general semiconductor layer(the p-type semiconductor layer or the n-type semiconductor layer), asemiconductor layer (a p-type semiconductor layer or an n-typesemiconductor layer) doped with a weaker dopant concentration than thegeneral semiconductor layer (the p-type semiconductor layer or then-type semiconductor layer). Furthermore, the first type semiconductorlayer 51 may further include an undoped semiconductor layer (e.g., u-GaNor the like). The same description may also be applied to the secondtype semiconductor layer 55.

In addition, as an example, the first type semiconductor layer 51 mayfurther include an electron blocking layer (EBL) or a hole blockinglayer (HBL). The electron blocking layer (EBL) may prevent electrons tobe moved to the light emitting layer 53 from being lost, and for thispurpose, may be formed at a position adjacent to the light emittinglayer 53. The hole blocking layer (HBL) may prevent holes to be moved tothe light emitting layer 53 from being lost, and may be formed at aposition adjacent to the light emitting layer 53. The same descriptionmay also be applied to the second type semiconductor layer 55.

According to an embodiment, the LED 50 may be an LED having a verticalstructure. For example, each of the plurality of LEDs 50 may have astructure in which one electrode (e.g., a lower electrode) is formed atthe bottom, and one electrode (e.g., an upper electrode) is formed atthe top. That is, as illustrated in FIGS. 3, 4A and 4B of thedisclosure, the LED 50 may be characterized by a structure for formingthe upper electrode and the lower electrode.

In particular, the display module 1 according to an embodiment of thedisclosure may have a stepless bottom contact structure, unlike a flipchip structure that requires protrusions (bumps or pads (electrodes))between the driving circuit layer 20 and the LED 50 to electricallyconnect the driving circuit layer 20 and the LED 50. According to anembodiment, in the flip chip structure, two pads may be provided on thelower portion of each of the first and second type semiconductor layers51 and 55 of the LED 50, and the two pads provided on the lower portionof the LED 50 and the two electrodes provided on the upper portion ofthe driving circuit layer 20 may be electrically connected to each otherthrough the bumps located therebetween. The flip chip structure is astructure in which an area of the first type semiconductor layer 51 issmaller than an area of the second type semiconductor layer 55 based ona horizontal plane, and an area of the light emitting layer 53 providedon the interface between the first type semiconductor layer 51 and thesecond type semiconductor layer 55 is also smaller than the area of thesecond type semiconductor layer 55.

According to an embodiment, the display module 1 having the steplessbottom contact structure does not need to form the protrusions such asthe pads and bumps by placing a step on each of the lower surfaces ofthe first and second type semiconductor layers 51 and 55 of the LED 50in that the display module 1 having the stepless bottom contactstructure may electrically connect the driving circuit layer 20 and theLED 50 through the intermediate substrate 40. That is, the intermediatesubstrate 40 may replace the protrusions such as the pads and bumps.

Accordingly, the display module 1 having the stepless bottom contactstructure may maximize the areas of the first type semiconductor layer51 and the second type semiconductor layer 55, and as a result, a lightemitting area of the light emitting layer 53 provided between the firsttype semiconductor layer 51 and the second type semiconductor layer 55may be maximized to improve light emission efficiency.

In addition, the display module 1 having the stepless bottom contactstructure may prevent the risk of short circuit occurrence of the twoelectrodes in that the two electrodes (or pads) of the LED 50 are formedat different positions, such as the upper and lower portions of the LED50. In particular, when the LED 50 is miniaturized, compared to the flipchip structure in which the two electrodes are positioned on the lowerportion of the LED 50, the stepless bottom contact structure in whichthe two electrodes are positioned on the upper and lower portions of theLED 50 may effectively prevent the risk of short circuit occurrence.

In addition, the LED 50 applied to the display module 1 according to thedisclosure is in the form of a package between a related art surfacemount device (SMD) and a chip size package (CSP), and may maintain theadvantages of size and cost, respectively, and at the same time solve anissue of Mura caused by light leakage in the related art light emittingelement. In addition, the structure of the display module 1 according tothe disclosure may improve light emission efficiency and yield in amanufacturing process.

Meanwhile, referring to FIG. 3, the display module 1 according to anembodiment of the disclosure may further include a passivation element57.

The passivation element 57 may be provided on sidewalls of the LED 50.For example, the passivation element 57 may be provided on sidewalls ofthe first type semiconductor layer 51, the light emitting layer 53, andthe second type semiconductor layer 55. Meanwhile, the upper electrode59 may be formed along the passivation element 57.

In this case, the passivation element 57 may perform functions forimproving light emission efficiency of the light emitting layer 53 andprotecting the semiconductor layers and the light emitting layer 53 fromthe outside, such as an insulating layer and impurities. According to anembodiment, the passivation element 57 may be implemented with variousinsulating materials such as Al₂O₃, SiN, and SiO₂. However, this is onlyan example, and the material of the passivation element 57 is notlimited to a specific material.

Meanwhile, according to an embodiment of the disclosure, referring toFIGS. 3, 4A and 4B, an emission direction of the LED 50 may be one of atop side, a bottom side, and a both side. Here, the top side, the bottomside, and the both side may refer to directions that proceed to theoutside of the LED 50, as illustrated by arrow directions illustrated inFIGS. 3, 4A, 4B. The emission direction may be determined according to aposition of the reflective electrode 56 (see FIGS. 4A and 4B) andpermeability (or transparency) of the material provided on the upper andlower portions of the LED 50.

Referring to FIG. 3, the emission direction of the LED 50 according toan embodiment of the disclosure may be the both side (or a double-sidedlight emission). In this case, the reflective layer is not inserted(included) inside the LED 50, and light emitted from the light emittinglayer 53 of the LED 50 may proceed in the top side and the bottom sideof the display module 1. Here, when the emission direction is the bothside, it is possible to display an image on a front surface (top side)and a rear surface (bottom side) of the display module 1.

In this case, each of the upper electrode 59, the first and secondconductive portions 48, 49, and 58, the driving circuit layer 20(comprising the first and second electrodes 28 and 29 of the drivingcircuit layer 20), and the substrate 10 may be made of a material thatcontributes to the permeability as a permeable material, that is, amaterial (e.g., glass, ITO, metal nano thin film, graphene, or the like)having high permeability and no light emission absorption.

Here, the upper electrode 59 included in the LED 50 may be implementedas a transparent electrode. Accordingly, light traveling in the top sideis not blocked by the transparent electrode, and may transmit throughthe transparent electrode. At this time, the transparent electrode mayrefer to an electrode having excellent electrical characteristics whiletransmitting light through high optical transparency. For example, thetransparent electrode may refer to an electrode having opticalcharacteristics of transmittance of 80% or more in a visible lightregion comprising blue, green, and red (e.g., light having a wavelengthin the range of 450 nm to 680 nm), and electrical characteristics of lowsheet resistance (Ω/sq) of hundreds or less and high conductivity (S/m)of hundreds or more.

Here, the transparent electrode may include at least one of carbon nanotube (CNT), graphene, or metal nano wire, and may also be implementedwith various materials such as indium tin oxide (ITO), conductivepolymer (e.g., Pedot:pss, or the like), Au, Pt, SnO₂, and TiO₂, whichhave high light transmittance and electrical conductivity. In addition,the transparent electrode may be implemented with a film material havingflexibility.

The transparent electrode may include CNT formed to have high electricalconductivity and transparent properties according to a structure of CNT(e.g., single wall CNT (SW-CNT), multi wall CNT (MW-CNT), and the like),a diameter of CNT, a molecular length of CNT, a concentration (ordensity) of CNT, and a density of hybrid material (e.g., Ag nano wireand the like).

Here, the first and second conductive portions 48, 49, and 58 mayinclude at least one of carbon nano tube (CNT), graphene, or metal nanowire having transparent properties.

In this case, the transparent electrode may be formed of the samematerial as the first and second conductive portions 48, 49, and 58 ofthe intermediate substrate 40.

Referring to FIGS. 4A and 4B, the LED 50 according to an embodiment ofthe disclosure may further include a reflective electrode 56. In thiscase, the reflective electrode 56 serves to adjust a traveling directionof the light emitted from the LED 50.

As an example, referring to FIG. 4A, the emission direction of the LED50 may be the top side (or a front light emission). In this case, thereflective layer is inserted (included) inside the LED 50, and the lightemitted from the light emitting layer 53 of the LED 50 may proceed inthe top side of the display module 1.

Here, the reflective electrode 56 may be provided on the lower portionof the first type semiconductor layer 51 as illustrated in FIG. 4A. Inthis case, the first type semiconductor layer 51 may be electricallyconnected to the driving circuit layer 20 through the reflectiveelectrode 56 and the first conductive portion 48 and 58 of theintermediate substrate 40. A method of forming the reflective electrode56 will be described later in a process of FIG. 6B.

Specifically, the reflective electrode 56 may reflect light in adirection different from a traveling direction of light emitted from thelight emitting layer 53 and incident on the reflective electrode 56. Forexample, when the reflective electrode 56 is provided on the lowerportion of the first type semiconductor layer 51, the reflectiveelectrode 56 may reflect light from an upper surface of the reflectiveelectrode 56 when light emitted in the bottom side from the lightemitting layer 53 reaches the reflective electrode 56. At this time, thedirection of the reflected light may be the top side of the lightemitting layer 53.

According to an embodiment, the reflective electrode 56 may be providedin a structure of a metal reflector or a distributed-bragg-reflector(DBR). In addition, the reflective electrode 56 may be made of amaterial such as aluminum (Al) or the like.

For example, the distributed-bragg-reflector structure may beimplemented as a multilayer structure in which two layers havingdifferent refractive indices are alternately stacked. Accordingly,Fresnel reflection occurs at an interface of each layer due to adifference in different refractive indexes of the two layers, anddepending on a material contained in the multilayer structure and athickness thereof, all reflected waves may cause constructiveinterference.

In this case, in order not to block the light traveling in the top side,the upper electrode 59 may be implemented as a material having highpermeability and no light emission absorption. That is, the upperelectrode 59 may be implemented as a transparent electrode, which willbe omitted in that it overlaps with the description described above.Meanwhile, each of the first and second conductive portions 58, 48, and49, the driving circuit layer 20 (comprising the first and secondelectrodes 28 and 29 of the driving circuit layer 20), and the substrate10 may be implemented as an impermeable material in that it is unrelatedto the traveling path of the light, but this is only an example and mayalso be implemented as a permeable material.

As another example, referring to FIG. 4B, the emission direction of theLED 50 may be the bottom side (or a rear light emission). In this case,the reflective layer is inserted (included) inside the LED 50, and thelight emitted from the light emitting layer 53 of the LED 50 may travelin the bottom side of the display module 1.

Here, the reflective electrode 56 may be provided on the upper portionof the second type semiconductor layer 55 as illustrated in FIG. 4B. Inthis case, the second type semiconductor layer 55 may be electricallyconnected to the second electrode 29 of the driving circuit layer 20through the reflective electrode 56, the upper electrode 59, and theconductive material 49 of the intermediate substrate 40.

For example, when the reflective electrode 56 is provided on the upperportion of the second type semiconductor layer 55, the reflectiveelectrode 56 may reflect light from a lower surface of the reflectiveelectrode 56 when light emitted in the top side from the light emittinglayer 53 reaches the reflective electrode 56. At this time, thedirection of the reflected light may be the bottom side of the lightemitting layer 53.

In this case, each of the first and second conductive portions 48, 49,and 58, the driving circuit layer 20 (comprising the first and secondelectrodes 28 and 29 of the driving circuit layer 20), and the substrate10 may be made of a material that contributes to the permeability as apermeable material, that is, a material (e.g., glass, ITO, metal nanothin film, graphene, or the like) having high permeability and no lightemission absorption. On the other hand, the upper electrode 59 may beimplemented as an impermeable material in that it is unrelated to thetraveling path of the light, but this is only an example and may also beimplemented as a permeable material.

Meanwhile, referring to FIGS. 4A and 4B, the display module 1 mayfurther include a black matrix 60.

The black matrix 60 may be provided on the intermediate substrate 40 ina region between the plurality of LEDs 50. That is, the black matrix 60may be provided on the intermediate substrate 40 in a region between anLED 50-1 and another LED 50-2.

The black matrix 60 may include a material that absorbs light andexhibits a black color. In addition, the black matrix 60 may include amaterial having high resistance properties (or insulating properties).According to an embodiment, the black matrix 60 may include variousmaterials such as CNT, polymer, and metal oxide.

In particular, the black matrix 60 may include CNT formed to have lowelectrical conductivity and light absorption properties according to astructure of CNT (e.g., single wall CNT (SW-CNT), multi wall CNT(MW-CNT), and the like), a diameter of CNT, a molecular length of CNT, aconcentration (or density) of CNT, and a density of hybrid material(e.g., Ag nano wire and the like).

According to an embodiment of the disclosure as described above, thereare advantages that the cost is reduced and the reliability is improvedby simplifying the process and solving the reduction in yield, in thatin order to connect the LED and the driving circuit layer, the electrode(e.g., the lower electrode) is provided on the lower portion of the LED,and there is no need to perform a process requiring heat treatment suchas anisotropic conductive film (ACF) or bump soldering.

In addition, the display module 1 according to the disclosure is astepless bottom bonding μ-LED structure, which has advantages that aseparate pad/bump is unnecessary on the lower portion of the LED forconnection, the driving circuit layer 20 and the LED 50 are directlybonded, and the ACF having a molding function is unnecessary as astepless structure.

In addition, there is an advantage in that the intermediate substrate 40on the lower portion of the LED 50 may simultaneously serve as an ohmiccontact and a binder. Due to these advantages, a contact area betweenthe circuit board and the LED element may be widened, and accordingly, aheat dissipation effect may be improved.

In addition, in the display module 1 according to the disclosure, theLED 50 may be easily transferred (or attached) to the driving circuitlayer 20 using the intermediate substrate 40.

Here, when the intermediate substrate 40 to which the LED 50 is attachedis attached to the driving circuit layer 20 (or the TFT layer), one or aplurality of LEDs 50 may be attached. At this time, the LEDs 50 of thesame color (or the same sub-pixel) may be simultaneously transferred inline units (e.g., column units or row units) or other aggregation units.In addition, when the LEDs 50 of the R, G, and B sub-pixels are arrangedand attached on the intermediate substrate 40, a unit pixel or aplurality of pixels may be simultaneously transferred to the drivingcircuit layer 20.

Accordingly, the display module 1 and the manufacturing method thereofaccording to the disclosure may improve the overall production yieldwhile improving a transfer speed for the LEDs 50.

FIG. 5 is a flowchart for describing a method for manufacturing adisplay module according to an embodiment of the disclosure.

Referring to FIG. 5, a manufacturing method of a display module 1 mayinclude an operation (S510) of forming an epitaxial film comprising alight emitting layer, a first type semiconductor layer, and a secondtype semiconductor layer, an operation (S520) of attaching the epitaxialfilm to an intermediate substrate 40 comprising a conductive material,an operation (S530) of patterning the attached epitaxial film to form alight emitting diode (LED) 50, and an operation (S540) of electricallyconnecting the LED 50 to a driving circuit layer 20 through theconductive material.

Hereinafter, each operation of the manufacturing method of the displaymodule according to the disclosure will be described together withreference to the accompanying drawings.

FIGS. 6A and 6B are views for describing an operation of forming anepitaxial film according to an embodiment of the disclosure.

According to an embodiment, in operation (S510), an epitaxial film 700may be formed on a growth substrate 600. According to an embodiment, theepitaxial film 700 may include a first type semiconductor layer 610, alight emitting layer 630, and a second type semiconductor layer 650.Accordingly, the first type semiconductor layer 610, the light emittinglayer 630, and the second type semiconductor layer 650 may be formed ona growth substrate 600 (S510).

Here, the growth substrate 600 may be a material or wafer suitable forgrowth (epitaxy) of a semiconductor. For example, the growth substrate600 may be implemented with a material such as silicon (Si), sapphire(Al₂SO₄), SiC, GaN, GaAs, or ZnO. On the other hand, the growthsubstrate 600 may be used as a substrate for epitaxial growth of thefirst type semiconductor layer 610, the light emitting layer 630, andthe second type semiconductor layer 650, and then separated and removedtherefrom.

When the growth substrate 600 is provided, the first type semiconductorlayer 610, the light emitting layer 630, and the second typesemiconductor layer 650 may be sequentially formed on the growthsubstrate 600. According to an example embodiment, when the growthsubstrate 600 is provided, the first type semiconductor layer 610, thelight emitting layer 630, and the second type semiconductor layer 650may be sequentially grown on the growth substrate 600. At this time, thedescription of the first type semiconductor layer 51, the light emittinglayer 53, and the second type semiconductor layer 55 of the LED 50described in FIG. 3 may be applied to each of the first typesemiconductor layer 610, the light emitting layer 630, and the secondtype semiconductor layer 650 in the same way, and thus the overlappingcontents will be omitted.

According to an embodiment, the growth of the semiconductor layer may beachieved by utilizing process technologies such as metalorganic vaporphase epitaxy (MOVPE), metal organic chemical vapor deposition (MOCVD),molecular beam epitaxy (MBE), liquid phase epitaxy (LPE), and vaporphase epitaxy (VPE).

Here, the epitaxial film 700 may include the first type semiconductorlayer 610, the light emitting layer 630, and the second typesemiconductor layer 650, and may refer to a film implemented in the formof a thin film having a thickness (a height in a vertical direction) ofseveral nanometers to tens of micrometers.

In addition, a size of the epitaxial film 700 (an area or a diagonallength on a plane having a height as a normal) may correspond to a sizeof the growth substrate 600. For example, the size of the epitaxial film700 may be substantially the same as the size of the growth substrate600 (e.g., a 10-inch wafer or the like), or may be smaller than the sizeof the growth substrate 600.

In addition, each of the first type semiconductor layer 610, the lightemitting layer 630, and the second type semiconductor layer 650 mayfurther include semiconductor layers having various properties, such asa hole blocking layer or an electron blocking layer, without limitingthe technical spirit of the disclosure.

Meanwhile, an emission direction of the display module 1 manufacturedaccording to the manufacturing method of the disclosure may be one of atop side, a bottom side, or both the top side and the bottom side.

The manufacturing method according to an embodiment of the disclosuremay not form a reflective electrode. In this case, the emissiondirection of the display module 1 manufactured through the followingoperations may be both the top side and the bottom side.

According to another embodiment, a manufacturing method may include anoperation of forming a reflective electrode. In this case, the emissiondirection of the display module 1 manufactured through the followingoperations may be one of the top side and the bottom side according to aposition of an electrode.

For instance, according to an embodiment illustrated in FIG. 6B, thefirst type semiconductor layer 610, the light emitting layer 630, andthe second type semiconductor layer 650 may be sequentially formed(grown) on the growth substrate 600, and a reflective electrode 660 maybe then formed on the second type semiconductor layer 650. That is, whenthe reflective electrode 660 is formed in the state of FIG. 6A, thestate of FIG. 6B may be obtained. In this case, the emission directionof the display module 1 manufactured through the following operationsmay be the top side.

At this time, the reflective electrode 660 may be formed on the secondtype semiconductor layer 650 through processes such as atomic layerdeposition (ALD), e-beam evaporation, and sputtering. The reflectiveelectrode 660 may be formed to have a thickness (a height in a verticaldirection) of several nanometers to tens of micrometers.

Here, the reflective electrode 660 may be configured as a layercomprising a metal material (e.g., Al, Ag—Pd—Cu alloy, or the like). Inaddition, the reflective electrode 660 may be configured as a singlelayer or a plurality of layers. For example, the reflective electrode660 may be configured as a multi-film layer of a loop-layer structurecomprising a first reflective layer formed of aluminum, a secondreflective layer formed on the first reflective layer and formed ofaluminum nitride, and a third reflective layer formed on the secondreflective layer and formed of aluminum.

Meanwhile, various metal materials having high reflectivity may be usedfor the reflective electrode 660 described above, but the material ofthe reflective electrode 660 is not limited to a specific material andmay be implemented by being modified with various materials.

According to another example embodiment, a reflective electrode 660 maybe formed on the substrate 600, and then the first type semiconductorlayer 610, the light emitting layer 630, and the second typesemiconductor layer 650 may be sequentially formed on the reflectiveelectrode 660.

FIGS. 7A and 7B are cross-section views for describing an operation ofseparating the epitaxial film according to an embodiment of thedisclosure.

Referring to FIGS. 7A and 7B, the epitaxial film 700 may be separatedfrom the growth substrate 600. Here, the epitaxial film 700 may includethe first type semiconductor layer 610, the light emitting layer 630,and the second type semiconductor layer 650. According to an embodiment,the separation (removal) of the growth substrate 600 may be performed byvarious methods such as laser lift off (LLO), lift off, wet etching, andthe like.

As an example, referring to FIG. 7A, the first type semiconductor layer610, the light emitting layer 630, and the second type semiconductorlayer 650 may be sequentially formed on the growth substrate 600, andthe epitaxial film 700 comprising the first type semiconductor layer610, the light emitting layer 630, and the second type semiconductorlayer 650 may be separated from the growth substrate 600. That is, theepitaxial film 700 may be separated in the state as illustrated in FIG.6A. In this case, when the reflective electrode is formed before thesubsequent patterning operation, the emission direction may become thebottom side, and when the reflective electrode is not formed, theemission direction may become both side.

As another example, referring to FIG. 7B, the first type semiconductorlayer 610, the light emitting layer 630, the second type semiconductorlayer 650, and the reflective electrode 660 may be sequentially formedon the growth substrate 600, and the epitaxial film 700 comprising thefirst type semiconductor layer 610, the light emitting layer 630, thesecond type semiconductor layer 650, and the reflective electrode 660may be separated from the growth substrate 600. That is, the epitaxialfilm 700 may be separated in the state as illustrated in FIG. 6B. Inthis case, the emission direction may become the top side.

FIGS. 8A to 8C are views for describing an operation of forming anintermediate substrate according to an embodiment of the disclosure.Hereinafter, a method for manufacturing an intermediate substrate 800will be first described, and then step S520 will be described.

Referring to FIG. 8A, the intermediate substrate 800 may be formed byimpregnating a conductive material 810 with an adhesive material 820.That is, the intermediate substrate 800 may include the conductivematerial 810 and the adhesive material 820, and may be implemented as,for example, a prepreg containing the conductive material 810 and theadhesive material 820. Here, the description for the intermediatesubstrate 40, the conductive materials 48, 49, and 58, and the adhesivematerial 43 may be applied to each of the intermediate substrate 800,the conductive material 810, and the adhesive material 820 in the sameway, and thus, the overlapping contents will be omitted.

Referring to FIGS. 8A and 8B, one or more regions 825 of the adhesivematerial 820 of the intermediate substrate 800 may be removed. Here, theremoval of the adhesive material 820 formed in one or more regions 825is to form a conductive material in the removed portion. The positions(or interval) of one or more regions 825 may correspond to the positions(or interval) of the electrodes of the driving circuit layer 20 so thatthe conductive material and the electrodes of the driving circuit layer20 are electrically connected to each other.

At this time, in order to remove one or more regions 825 of the adhesivematerial 820, photolithography and etching processes may be used.

For example, an exposed region (or an unexposed region) may be removeddepending on the type of photoresist (e.g., positive PR or negative PR)by forming a photoresist on the adhesive material 820 and exposing andthen developing only a specific region of the photoresist formed on theadhesive material 820 through a mask having openings (or lighttransmission portions) formed therein.

In this case, as illustrated in FIG. 8A, in order to remove the adhesivematerial 820 formed in one or more regions 825, as illustrated in FIG.8B, an ashing process (e.g., 02 gas, plasma surface treatment, organicfilm removal, or the like) may be performed on one or more regions 845where a photoresist 840 does not remain.

In addition, referring to FIGS. 8B and 8C, in a state in which thephotoresist 840 is formed on the adhesive material 830, a conductivematerial 850 may be formed in one or more regions 845 from which theadhesive material 820 is removed. At this time, the remainingphotoresist 840 serves to prevent the conductive material from beingformed on the adhesive material 830. Meanwhile, as a method of formingthe conductive material 850, spray coating, MOCVD, MOVPE, MBEdeposition, or the like may be used.

Thereafter, by removing the remaining photoresist 840, the intermediatesubstrate 800 may include a prepreg containing the conductive materials810 and 850 and the adhesive material 830 as illustrated in FIG. 8C.

Meanwhile, the conductive materials 810 and 850 may include at least oneof carbon nano tube (CNT), graphene, or metal nano wire, and theadhesive material 830 may include at least one of epoxy, polyimide, orphenol.

On the other hand, the above-described operation of forming theintermediate substrate 800 was described as being performed after theoperation (S510) of forming the epitaxial film 700, but may also beperformed prior to the operation (S510) of forming the epitaxial film700 or simultaneously performed in parallel to the operation (S510) offorming the epitaxial film 700.

FIGS. 9A to 9D are views for describing an operation of bonding anepitaxial film onto an intermediate substrate according to an embodimentof the disclosure.

Referring to FIGS. 9A and 9B, the epitaxial film 700 may be attached(bonded) on to the intermediate substrate 800. At this time, theepitaxial film 700 may be directly-bonded onto the intermediatesubstrate 800 without other media (e.g., soldering bumps, ACF, and thelike).

Specifically, the epitaxial film 700 separated from the growth substrate600 may be attached (or bonded) onto the intermediate substrate 800. Forexample, one surface (e.g., the upper surface of the second typesemiconductor layer 650 or the upper surface of the reflective electrode660) of the epitaxial film 700 opposite to the surface (e.g., the lowersurface of the first type semiconductor layer 610) separated from thegrowth substrate 600 may be attached (or bonded) onto the intermediatesubstrate 800. That is, the top and bottom of the epitaxial film 700 maybe changed to directly bond onto the intermediate substrate 800.

Here, in the intermediate substrate 800, the conductive material 810 maybe positioned on the upper portion thereof, and the adhesive material830 may be positioned on the lower portion thereof. That is, theepitaxial film 700 may be attached to the intermediate substrate 800 sothat the second type semiconductor layer 650 of the epitaxial film 700abuts (faces) the conductive material 810 of the intermediate substrate800.

At this time, the epitaxial film 700 may be attached onto theintermediate substrate 800 by the van der Waals force of the conductivematerial 810.

According to an embodiment, the epitaxial film 700 may be attached ontothe intermediate substrate 800 through various methods such as reel toreel, roller pressing, vacuum pressing, and pressing in which a platemoves and presses in a vertical direction. For example, in the case ofthe roller pressing method, the epitaxial film 700 and the intermediatesubstrate 800 may be disposed in one direction. In this case, when theroller presses the epitaxial film 700 while rotating, the epitaxial film700 may be attached onto the roller while being wound. When the rollerpresses the intermediate substrate 800 while rotating again, theepitaxial film 700 attached to the roller may be transferred to andattached onto the intermediate substrate 800.

Referring to FIGS. 7A and 9A, the epitaxial film 700 may be attached (orbonded) onto the intermediate substrate 800 so that the first typesemiconductor layer 610 of the epitaxial film 700 in a state in whichthe reflective electrode is not formed is positioned on the upperportion thereof, and the second type semiconductor layer 650 opposite tothe position of the first type semiconductor layer 610 of the epitaxialfilm 700 is positioned on the lower portion thereof. That is, theepitaxial film 700 may be attached (or bonded) onto the intermediatesubstrate 800 so that one surface of the second type semiconductor layer650 of the epitaxial film 700 contacts the upper portion of theintermediate substrate 800.

Here, as an example, when the patterning operation (S530) is performedwithout forming the reflective electrode in the state of FIG. 9A, theemission direction may become both side. As another example, when thepatterning operation (S530) is performed after forming the reflectiveelectrode as illustrated in FIG. 9C in the state of FIG. 9A, theemission direction may become the bottom side.

Specifically, referring FIG. 9C, after the epitaxial film 700 comprisingthe first type semiconductor layer 610, the light emitting layer 630,and the second type semiconductor layer 650 is attached (or bonded) ontothe intermediate substrate 800, a reflective electrode 660′ may be thenformed on the upper portion of the first type semiconductor layer 610.At this time, the reflective electrode 660′ may be formed on the firsttype semiconductor layer 610 through processes such as atomic layerdeposition (ALD), e-beam evaporation, and sputtering. The contents ofthe reflective electrode 660 described above may be applied to thereflective electrode 660′ in the same way, and thus, the overlappingcontents will be omitted. In this case, because the reflective electrode660′ is formed on the upper portion of the epitaxial film 700, theemission direction may become the bottom side.

On the other hand, as another example, referring to FIGS. 7B and 9B, theepitaxial film 700 may be attached (or bonded) onto the intermediatesubstrate 800 so that the first type semiconductor layer 610 of theepitaxial film 700 in a state in which the reflective electrode isformed is positioned on the upper portion thereof, and the reflectiveelectrode 660 opposite to the position of the first type semiconductorlayer 610 of the epitaxial film 700 is positioned on the lower portionthereof. That is, the epitaxial film 700 may be attached (or bonded)onto the intermediate substrate 800 so that one surface of thereflective electrode 660 of the epitaxial film 700 contacts the upperportion of the intermediate substrate 800. In this case, because thereflective electrode 660 is formed on the lower portion of the epitaxialfilm 700, the emission direction may become the top side.

FIGS. 10A to 10F are views for describing an operation of patterning anepitaxial film according to an embodiment of the disclosure. Here, FIGS.10A to 10C are views for describing an operation of patterning theepitaxial film 700 in a state in which the reflective electrode is notformed, as illustrated in FIG. 9A, and FIGS. 10D and 10E are views fordescribing a structure of the LED 50 generated as a result ofpatterning, as illustrated in FIGS. 10A and 10B, the epitaxial film 700in a state in which the reflective electrodes 660 and 660′ are formed asillustrated in FIGS. 9B and 9C, respectively.

Referring to FIG. 10A to 10F, the epitaxial film 700 attached onto theintermediate substrate 800 may be patterned to form a light emittingdiode (LED) 50 (S530). At this time, the LED 50 formed as a result ofthe patterning may include a light emitting layer 53, and a first typesemiconductor layer 51 and a second type semiconductor layer 55 formedon upper and lower portions of the light emitting layer 53,respectively. Here, the LED 50 may refer to one of the plurality of LEDs50-1 and 50-2 as illustrated in FIGS. 10C-10E.

Specifically, referring to FIGS. 10A and 10B, the epitaxial film 700bonded onto the intermediate substrate 800 may be patterned. At thistime, a photolithography process and an etching process may be used.

For example, after a photoresist 1010 is formed on the first typesemiconductor layer 610, a mask 1020 in which the openings (or the lighttransmission portions) are formed may be aligned on the photoresist1010, and specific regions 1011 of the photoresist 1010 may be exposedthrough the openings of the mask 1020.

In this case, the photoresist 1010 may be developed to remove an exposedregion (or an unexposed region) as illustrated in FIG. 10B, and anetching process may be performed on one or more regions 1030 in whichthe photoresist 1013 does not remain. As a result, one or more regions1030 may be removed. At this time, as the etching process, methods suchas a wet etching, a dry etching, plasma, a physical etching, and achemical etching may be used. Here, one or more regions 1030 may be agrid-shaped region, and may include a conductive material 49 and may bea region excluding the conductive material 48.

Thereafter, by removing the remaining photoresist 1013, as illustratedin FIGS. 10C-10F, the epitaxial film 700 may be formed in the form inwhich the plurality of LEDs 50-1 and 50-2 are separated from each other.In this case, the first type semiconductor layers 51 of the LEDs 50-1and 50-2 may be formed based on the second type semiconductor layer 650of the epitaxial film 700, the light emitting layers 53 of the LEDs 50-1and 50-2 may be formed based on the light emitting layer 630 of theepitaxial film 700, and a plurality of second type semiconductor layers55 of the LEDs 50-1 and 50-2 may be formed based on the first typesemiconductor layer 610 of the epitaxial film 700.

That is, the epitaxial film 700 attached (or bonded) onto theintermediate substrate 800 may be patterned as illustrated in FIGS. 10Aand 10B to form the plurality of LEDs 50-1 and 50-2 on the intermediatesubstrate 40 as illustrated in FIGS. 10C and 10F.

In addition, a portion of the conductive material 810 formed on theintermediate substrate 40 may be removed, and a remaining portion of theconductive material 810 may remain. Here, the portions remaining in theintermediate substrate 40 as illustrated in FIG. 10C will be referred toas the conductive materials 58 and 48. In addition, the adhesivematerial 43 may remain in the intermediate substrate 40. That is, theintermediate substrate 40 that has been subjected to the patterningoperation may include the conductive materials 48 and 58 and theadhesive material 43.

On the other hand, in the display module 1, according to the resolution,size, number of pixels, and the like, a pitch, which is an intervalbetween the LEDs 50-1 and 50-2, may be designed (predetermined).Accordingly, the electrodes (e.g., the first electrode 28 and the like)of the driving circuit layer 20 to which the LEDs 50-1 and 50-2 arebonded may be disposed (formed) to be spaced apart from each other at aninterval (e.g., an interval in an error range) corresponding to thepredetermined pitch.

Here, because the intermediate substrate 40 applied to the displaymodule 1 is implemented with a material having elasticity or stretch,the intermediate substrate 40 may be stretched in a direction in which aforce is applied when a physical force is applied thereto. Accordingly,an interval between the conductive materials 48 of the intermediatesubstrate 40 (or an interval between the LEDs 50-1 and 50-2) may also beincreased.

In the manufacturing method according to an embodiment of thedisclosure, the LEDs 50-1 and 50-2 having an interval smaller than apredetermined pitch may be formed based on the epitaxial film 700attached onto the intermediate substrate 40 by using elasticity orstretch of the intermediate substrate 40, and the physical force (e.g.,tensile force) in a horizontal direction may be applied to theintermediate substrate 40 so that the interval between the LEDs 50-1 and50-2 is the predetermined pitch.

Specifically, the conductive materials 48 of the intermediate substrate40 may be formed to be spaced apart from each other at an interval(e.g., 40 um) smaller than the predetermined pitch (e.g., 50 um). Inthis case, after the epitaxial film 700 is attached onto theintermediate substrate 800, one region 1030 of the epitaxial film 700and the intermediate substrate 800 may be removed through the patterningoperation to form the mutually separated (individualized) LEDs 50-1 and50-2. Here, the interval between the LEDs 50-1 and 50-2 may be aninterval (e.g., 40 um) smaller than the predetermined pitch (e.g., 50um), and may be the same value as a horizontal length of one region 1030removed from the epitaxial film 700. Thereafter, a physical force (e.g.,tensile force) in the horizontal direction may be applied to theintermediate substrate 40 so that the interval between the LEDs 50-1 and50-2 is substantially the same interval (e.g., 50 um, comprising theerror range) as the predetermined pitch.

According to an embodiment of the disclosure as described above, thesize (area) of one region 1030 removed from the epitaxial film 700 maybe smaller, and accordingly, a portion (area) discarded from theepitaxial film 700 grown through the growth substrate 600 (e.g., awafer) having a limited size may be reduced, thereby improving anefficiency of resources, and the degree of integration of the LEDs 50-1and 50-2 formed based on the epitaxial film 700 may be increased.

In addition, according to an embodiment of the disclosure, because theinterval between the conductive materials 48 and between the LEDs 50-1and 50-2 may be freely adjusted by using the elasticity or stretch ofthe intermediate substrate 40, process error such as error in theinterval of the electrodes of the driving circuit layer may be solved,and display devices having various sizes or various pitches may bemanufactured without having to build a separate production line for eachsize. For example, depending on the degree of tension force applied tothe same 9.5-inch display module, it is possible to manufacture displaydevices of various sizes, such as a 10-inch display device and an11-inch display device.

On the other hand, when the epitaxial film 700 in a state in which thereflective electrode is not formed as illustrated in FIG. 9A ispatterned, the LEDs 50-1 and 50-2 that do not include the reflectiveelectrode may be formed as illustrated in FIG. 10C. In this case,because each of the LEDs 50-1 and 50-2 does not include the reflectiveelectrode, the emission direction may become both side.

On the other hand, when the patterning operation as illustrated in FIGS.10A and 10B is performed for the epitaxial film 700 in the state inwhich the reflective electrode 660 is formed on the lower portion of theepitaxial film 700 as illustrated in FIG. 9B, the LEDs 50-1 and 50-2having the reflective electrode 56 positioned on the lower portionsthereof may be formed as illustrated in FIG. 10D. In this case, becauseeach of the LEDs 50-1 and 50-2 includes the reflective electrode 56formed on the lower portion thereof, the emission direction may becomethe top side.

On the other hand, when the patterning operation as illustrated in FIGS.10A and 10B is performed for the epitaxial film 700 in the state inwhich the reflective electrode 660′ is formed on the upper portion ofthe epitaxial film 700 as illustrated in FIG. 9C, the LEDs 50-1 and 50-2having a reflective electrode 56′ positioned on the upper portionsthereof may be formed as illustrated in FIG. 10E. In this case, becauseeach of the LEDs 50-1 and 50-2 includes the reflective electrode 56′formed on the upper portion thereof, the emission direction may becomethe bottom side.

FIGS. 11A to 11C are views for describing a method of forming apassivation according to an embodiment of the disclosure.

Referring to FIGS. 11A to 11C, the manufacturing method according to anembodiment of the disclosure may further include an operation of forminga passivation element 57 on sidewalls of the LEDs 50-1 and 50-2.According to an embodiment, the passivation element 57 may be formed bya deposition method such as atomic layer deposition, electron beamdeposition, sputtering, or the like. The passivation 57 may include aninsulating material, and the detailed content thereof will be omitted inthat it overlaps with the content described above.

As an example, as illustrated in FIG. 11A, in the case of the LEDs 50-1and 50-2 in which the reflective electrode is not formed, thepassivation element 57 may be formed on the side walls of the LEDs 50-1and 50-2. Specifically, the passivation element 57 may be formed tosurround a sidewall (or a side surface) of each of the first typesemiconductor layer 51, the light emitting layer 53, the second typesemiconductor layer 55, and the conductive material 58 of the LED 50.

As another example, as illustrated in FIGS. 11B and 11C, in the case ofthe LEDs 50-1 and 50-2 in which the reflective electrodes 56 and 56′ areformed, the passivation element 57 may be formed on the side walls ofthe LEDs 50-1 and 50-2. Specifically, the passivation element 57 may beformed to surround a sidewall (or a side surface) of each of the firsttype semiconductor layer 51, the light emitting layer 53, the secondtype semiconductor layer 55, the conductive material 58, and thereflective electrodes 56 and 56′ of the LED 50.

Accordingly, since the passivation element 57 includes an insulatingmaterial, the light emission efficiency of the light emitting layer 53may be improved, and the semiconductor layer and the light emittinglayer 53 may be protected from the outside, such as an insulating layerand impurities.

FIGS. 12A and 12B are views for describing an inspection methodaccording to an embodiment of the disclosure. FIGS. 12A and 12Billustrate the LEDs 50-1 and 50-2 in the state in which the reflectiveelectrode is not formed, but this is for convenience of explanationonly, and may also be applied to the LEDs 50-1 and 50-2 in the state inwhich the reflective electrodes 56 and 56′ are formed in the same way.

In the manufacturing method according to an embodiment of thedisclosure, before performing the operation (S540) of connecting the LED50-1 and 50-2 to the driving circuit layer 20, an operation ofinspecting defects of the plurality of LEDs 50-1 and 50-2 may beperformed.

Referring to FIGS. 12A and 12B, lower and upper inspection substrates1210 and 1220 may be attached to the upper and lower portions of theintermediate substrate 40 in a state in which the plurality of LEDs 50-1and 50-2 are bonded.

Here, the inspection substrates 1210 and 1220 may be formed (ormanufactured) as a structure for evaluating optical or electricalproperties of each of the plurality of LEDs 50-1 and 50-2 bonded ontothe intermediate substrate 40.

The lower inspection substrate 1210 may include a base substrate 1211and a plurality of first electrodes 1218. Here, the plurality of firstelectrodes 1218 may be disposed in the same manner as the plurality offirst electrodes 28 of the driving circuit layer 20 illustrated in FIG.13, and may have the same polarity (e.g., anode or cathode).

The upper inspection substrate 1220 may include a base substrate 1221,an adhesive layer 1223, and a plurality of second electrodes 1229. Here,the plurality of second electrodes 1229 may be disposed in the samemanner as the plurality of second electrodes 29 of the driving circuitlayer 20 illustrated in FIG. 13, and may have the same polarity (e.g.,anode or cathode). Here, the second electrode 1229 may be formed along aline in which the plurality of LEDs 50 are formed so as to be connectedto the plurality of LEDs 50. In addition, a height h2 from a lowersurface of the base substrate 1221 to lower surfaces of the plurality ofsecond electrodes 1229 may be the same as a height h1 of the LED 50-1.This is because when h2 is smaller than h1, the upper inspectionsubstrate 1220 may press the plurality of LEDs 50-1 and 50-2 and destroythe plurality of LEDs 50-1 and 50-2. Accordingly, the height h2 from thelower surface of the base substrate 1221 to the lower surfaces of theplurality of second electrodes 1229 may be adjustable according to theheights h1 of various LEDs 50-1.

In this case, as illustrated in FIG. 12B, the inspection substrates 1210and 1220 may generate driving signals for turning on the plurality ofLEDs 50-1 and 50-2, and accordingly, an optical inspection or the likeof checking whether or not the plurality of LEDs 50-1 and 50-2 aredefective may be performed.

Specifically, the optical inspection can identify whether or not theplurality of LEDs 50-1 and 50-2 are turned on through an image capturedby a vision camera such as automatic optical inspection (AOI).

In particular, when it is identified that an LED which is not turned on(hereinafter, a defective LED) occurs because an interval between theplurality of first electrodes 1218 of the lower inspection substrate1210 is larger than the interval between the conductive materials 48,the intermediate substrate 40 may be stretched such that the intervalbetween the conductive materials 48 of the intermediate substrate 40coincides with the interval of the plurality of first electrodes 1218 ofthe lower inspection substrate 1210, by detaching the intermediatesubstrate 40 corresponding to a region (coordinate) of the defective LEDfrom the lower inspection substrate 1210, and then applying a force inthe horizontal direction to the intermediate substrate 40. This is touse the elasticity or stretch of the intermediate substrate 40. Inaddition, the intermediate substrate 40 may be attached to the lowerinspection substrate 1210 such that the conductive materials 48 of theintermediate substrate 40 contact the plurality of first electrodes 1218of the lower inspection substrate 1210. Thereafter, the opticalinspection may be performed through the lower and upper inspectionsubstrates 1210 and 1220 attached to the intermediate substrate 40again.

On the other hand, when the defective LED is identified, the LED and theintermediate substrate 40 corresponding to the identified region may bedetached and removed. That is, some regions may be detached from theintermediate substrate 40 through various methods (a physical force, achemical method, and the like).

Here, when the inspection operation is completed, the inspectionsubstrates 1210 and 1220 may be detached from the intermediate substrate40 as illustrated in FIG. 12A.

Thereafter, the LED 50 may be electrically connected to the drivingcircuit layer 20 through the conductive material (S540). This will bedescribed in more detail with reference to FIGS. 13A to 13E and 14A to14D.

FIGS. 13A to 13E are views for describing an operation of bonding anintermediate substrate onto a driving circuit layer according to anembodiment of the disclosure.

Here, FIG. 13A illustrates a state before the intermediate substrate 40on which the LEDs 50-1 and 50-2 having the state in which the reflectiveelectrode is not formed, that is, a structure in which the emissiondirection is both side is bonded onto the driving circuit layer 20,according to an embodiment of the disclosure.

Referring to FIG. 13A, the intermediate substrate 40 may be attachedonto the driving circuit layer 20 disposed on the substrate 10 toelectrically connect the first type semiconductor layers 51 of theplurality of LEDs 50 attached onto the intermediate substrate 40 to thedriving circuit layer 20.

Here, the driving circuit layer 20 may include a plurality of pixelcircuits 21 and a first electrode 28 and a second electrode 29electrically connected to each of the plurality of pixel circuits 21.Here, the description of the driving circuit layer 20 overlaps thecontents described above and will be thus omitted.

Specifically, the intermediate substrate 40 may be attached onto thedriving circuit layer 20 through the adhesive material 43. Here, theintermediate substrate 40 may be attached onto the driving circuit layer20 so that the lower portion of the intermediate substrate 40 ispositioned on the driving circuit layer 20 in a state in which theplurality of LEDs 50-1 and 50-2 are bonded onto the intermediatesubstrate 40. The intermediate substrate 40 may be directly bonded ontothe driving circuit layer 20.

In this case, the first type semiconductor layer 51 of each of theplurality of LEDs 50 may be electrically connected to the firstelectrode 28 of the driving circuit layer 20 through the conductivematerials 48 and 58.

According to an embodiment, the intermediate substrate 40 may beattached onto the driving circuit layer 20 through various methods suchas reel to reel, roller pressing, vacuum pressing, and pressing in whicha plate moves and presses in a vertical direction. For example, in thecase of the roller pressing method, the intermediate substrate 40 onwhich the LEDs 50 are formed and the driving circuit layer 20 (or thesubstrate 10 on which the driving circuit layer 20 is formed) may bedisposed in one direction. In this case, when the roller presses theintermediate substrate 40 while rotating, the intermediate substrate 40may be attached onto the roller while being wound. When the rollerpresses the driving circuit layer 20 while rotating again, theintermediate substrate 40 attached to the roller may be transferred toand attached onto the driving circuit layer 20.

On the other hand, when the intermediate substrate 40 in the state inwhich the LEDs 50-1 and 50-2 having the structure in which the emissiondirection is the top side are formed is bonded onto the driving circuitlayer 20 according to an embodiment of the disclosure, the conductivematerial 48 may be electrically connected to the first electrode 28 ofthe driving circuit layer 20, and the conductive material 49 may beelectrically connected to the second electrode 29 of the driving circuitlayer 20, as illustrated in FIG. 13B. In this case, the first typesemiconductor layers 51 of the LEDs 50-1 and 50-2 may be electricallyconnected to the first electrodes 28 of the driving circuit layer 20through the reflective electrodes 56 formed on the lower portion of theLEDs 50-1 and 50-2 and the conductive materials 58 and 48.

On the other hand, when the intermediate substrate 40 in the state inwhich the LEDs 50-1 and 50-2 having the structure in which the emissiondirection is the bottom side are formed is bonded onto the drivingcircuit layer 20, the conductive material 48 may be electricallyconnected to the first electrode 28 of the driving circuit layer 20, andthe conductive material 49 may be electrically connected to the secondelectrode 29 of the driving circuit layer 20, as illustrated in FIG.13C. In this case, the first type semiconductor layers 51 of the LEDs50-1 and 50-2 may be electrically connected to the first electrodes 28of the driving circuit layer 20 through the conductive materials 58 and48.

The intermediate substrate 40 according to an embodiment of thedisclosure as described above may be directly bonded onto the drivingcircuit layer 20 without other media.

According to an embodiment, as illustrated in FIG. 13D, the intermediatesubstrate 40 may be attached onto the driving circuit layer 20 in unitsof pixels 100-1 and 100-2. That is, the intermediate substrate 40comprising the LEDs 50 corresponding to the pixels 100-1 and 100-2 maybe attached onto the driving circuit layer 20. Here, each of the pixels100-1 and 100-2 may include a single LED 50, or may include a pluralityof LEDs 50-1, 50-2, and 50-3.

As another example, as illustrated in FIG. 13E, the intermediatesubstrate 40 may be attached onto the driving circuit layer 20 in unitsof columns (or rows) of the LEDs 50. That is, an intermediate substrate40 comprising at least one column (or row) of LEDs 50 may be attachedonto the driving circuit layer 20. Here, the LEDs 50-1, 50-2, and 50-3corresponding to one column (or row) may be LEDs formed to emit the samecolor (e.g., red) (i.e., sub-pixels of the same type (color)).

Accordingly, the display module 1 and the manufacturing method thereofaccording to the disclosure may improve a transfer speed for theplurality of LEDs 50 and may improve the overall production yield.

On the other hand, the intermediate substrate 40 may include a prepregto have elasticity or stretch and adhesiveness. Accordingly, when adefective LED occurs among the plurality of LEDs 50-1 and 50-2, thedefective LED and the intermediate substrate 40 of the portioncomprising the defective LED may be removed together as a sticker. Adefect may be repaired by attaching the intermediate substrate 40 towhich the plurality of separate LEDs 50-1 and 50-2 are bonded to theportion where the intermediate substrate 40 on the driving circuit layer20 is removed.

FIGS. 14A to 14D are views for describing a display module manufacturedaccording to an embodiment of the disclosure. Here, FIG. 14A is a viewfor describing a structure in which the emission direction is both sideas the LEDs 50-1 and 50-2 in a state in which a reflective electrode isnot formed according to an embodiment of the disclosure, FIG. 14B is aview for describing a structure in which an emission direction is thetop side as the LEDs 50-1 and 50-2 in a state in which the reflectiveelectrode 56 is formed on the lower portions thereof according to anembodiment of the disclosure, FIG. 14C is a view for describing astructure in which an emission direction is the bottom side as the LEDs50-1 and 50-2 in a state in which the reflective electrode 56′ is formedon the upper portions thereof according to an embodiment of thedisclosure, and FIG. 14D is a view illustrating an arrangement of aplurality of LEDs 50-1 and 50-2 in the display module.

Referring to FIGS. 14A to 14D, the second type semiconductor layers 55of the plurality of LEDs 50-1 and 50-2 may be electrically connected tothe driving circuit layer 20.

According to an embodiment, an upper electrode 59 of each of theplurality of LEDs 50-1 and 50-2 may be formed. Here, the upper electrode59 may include at least one of carbon nano tube (CNT), graphene, ormetal nano wire, and may be also be implemented as a flexible electrodehaving flexibility. This overlaps the contents described above, andthus, detailed contents will be omitted.

Here, the upper electrode 59 may be formed through various methods suchas a spraying method (e.g., spraying), a lamination method,photolithography, MOVPE, MOCVD, and MBE.

Specifically, the upper electrode 59 may be formed along a side surfaceof the LED 50. In this case, the second type semiconductor layer 55 maybe electrically connected to the second electrode 29 of the drivingcircuit layer 20 through the transparent electrode 59 and the conductivematerial 49 of the intermediate substrate 40.

According to an embodiment of the disclosure, the upper electrode 59 ofeach of the plurality of LEDs 50-1 and 50-2 may be formed along thepassivation 57. In this case, the second type semiconductor layer 55 ofeach of the plurality of LEDs 50-1 and 50-2 may be electricallyconnected to the second electrode 29 of the driving circuit layer 20through the upper electrode 59.

Meanwhile, as an example of the disclosure, when the emission directionis both side as illustrated in FIG. 14A or is the top side asillustrated in FIG. 14B, the upper electrode 59 may be configured as atransparent electrode having high light transmittance and electricalconductivity.

For example, the upper electrode 59 may include CNT having highelectrical conductivity and transparent properties according to astructure of CNT (e.g., single wall CNT (SW-CNT), multi wall CNT(MW-CNT), and the like), a diameter of CNT, a molecular length of CNT, aconcentration (or density) of CNT, and a density of hybrid material(e.g., Ag nano wire and the like).

On the other hand, when the emission direction is the bottom side asillustrated in FIG. 14C, the upper electrode 59 may be configured as anelectrode having high electrical conductivity properties. At this time,the upper electrode 59 does not need to be made of a material having ahigh light transmittance in that it is not a traveling path of light,but is not limited thereto and may be made of various materials.

As described above, in the manufacturing method of the display module 1according to an embodiment of the disclosure, the display module 1having the stepless bottom contact structure may be manufactured, unlikethe flip chip structure that requires the protrusions (bumps or pads(electrodes)) between the driving circuit layer 20 and the LED 50 toelectrically connect the driving circuit layer 20 and the LED 50.

Here, the display module 1 having the stepless bottom contact structuredoes not need to form the protrusions such as the pads and bumps byplacing a step on each of the lower surfaces of the first and secondtype semiconductor layers 51 and 55 of the LED 50 in that the displaymodule 1 having the stepless bottom contact structure may electricallyconnect the driving circuit layer 20 and the LED 50 through theintermediate substrate 40. That is, the intermediate substrate 40 mayreplace the protrusions such as the pads and bumps.

Accordingly, the display module 1 having the stepless bottom contactstructure may maximize the areas of the first type semiconductor layer51 and the second type semiconductor layer 55, and as a result, thelight emitting area of the light emitting layer 53 formed between thefirst type semiconductor layer 51 and the second type semiconductorlayer 55 may be maximized to improve the light emission efficiency.

In addition, the display module 1 having the stepless bottom contactstructure may prevent the risk of short occurrence of the two electrodesin that the two electrodes (or pads) of the LED 50 are formed atdifferent positions, such as the upper and lower portions of the LED 50.In particular, when the LED 50 is miniaturized, compared to the flipchip structure in which the two electrodes are positioned on the lowerportion of the LED 50, the stepless bottom contact structure in whichthe two electrodes are positioned on the upper and lower portions of theLED 50 may effectively prevent the risk of short circuit occurrence.

FIG. 15 is a view for describing a black matrix according to anembodiment of the disclosure.

Referring to FIG. 15, the manufacturing method according to anembodiment of the disclosure may further include an operation of forminga black matrix 60 on the intermediate substrate 40 in a region betweenthe plurality of LEDs 50-1 and 50-2.

Here, the black matrix 60 may include a material that absorbs light andexhibits a black color. In addition, the black matrix 60 may include amaterial having high resistance properties (or insulating properties).According to an embodiment, the black matrix 60 may include variousmaterials such as CNT, polymer, and metal oxide, and may be formedthrough a spraying method, a lamination method, MOCVD, MOVPE, MBEdeposition, or the like.

In particular, when the CNT is used as the black matrix 60, CNT havinglow electrical conductivity and light absorption properties may be usedaccording to a structure of CNT (e.g., single wall CNT (SW-CNT), multiwall CNT (MW-CNT), and the like), a diameter of CNT, a molecular lengthof CNT, a concentration (or density) of CNT, and a density of hybridmaterial (e.g., Ag nano wire or the like).

Accordingly, the manufacturing method according to an embodiment of thedisclosure has an effect that the black matrix 60 may be formed througha simpler process, and the black matrix 60 having excellent externallight absorption properties may be formed.

According to the diverse embodiments of the disclosure as describedabove, the display module and the manufacturing method thereof thatsolve various problems such as a defect rate, a non-illumination rate,and a reduction in yield of the related art μ-LED process whilealleviating the limitations of the related art μ-LED structure may beprovided.

In addition, according to one or more embodiments of the disclosure, aneffect of reducing the cost and an effect of improving the reliabilityare expected by solving the reducing in yield through simplification ofthe process and solving of issues of the process such as the shortcircuit occurrence and the non-illumination defect.

While the drawings accompanying the disclosure are provided to helpunderstand the technical spirit of the disclosure, the technical spiritof the disclosure is not limited by the relative sizes or intervals ofvarious elements, regions, and the like illustrated in the drawings.

One or more embodiments of the disclosure may be implemented by softwarecomprising instructions that are stored in machine (e.g., acomputer)-readable storage media. The machine is a device that invokesthe stored instructions from the storage media and is operable accordingto the invoked instructions, and may include an electronic deviceaccording to the disclosed embodiments. When the commands are executedby the processor, the processor may perform functions corresponding tothe commands, either directly or using other components under thecontrol of the processor. The commands may include codes generated orexecuted by a compiler or an interpreter. The machine-readable storagemedia may be provided in the form of non-transitory storage media. Here,the term ‘non-transitory’ means that the storage medium does not includea signal and is tangible, but does not distinguish whether data isstored semi-permanently or temporarily in the storage medium.

The method according to one or more embodiments may be provided as beingincluded in a computer program product. The computer program product maybe traded as a product between a seller and a purchaser. The computerprogram product may be distributed in the form of a machine readablestorage medium (e.g., a compact disc read only memory (CD-ROM)), oronline through an application store (e.g., PlayStore™). In case of theonline distribution, at least a portion of the computer program productmay be at least temporarily stored or be temporarily generated in astorage medium such as a server of a manufacturer, a server of anapplication store, or a memory of a relay server.

Each of the components (e.g., modules or programs) according to the oneor more embodiments may include a single entity or a plurality ofentities, and some sub-components of the sub-components described abovemay be omitted, or other sub-components may be further included in theone or more embodiments. Alternatively or additionally, some components(e.g., modules or programs) may be integrated into one entity to performthe same or similar functions performed by the respective componentsprior to the integration. The operations performed by the module, theprogram, or other component, in accordance with the one or moreembodiments may be executed in a sequential, parallel, iterative, orheuristic manner, or at least some operations may be executed in adifferent order or omitted, or other operations may be added.

Although the embodiments of the disclosure have been illustrated anddescribed hereinabove, the disclosure is not limited to the specificembodiments described above, but may be variously modified by thoseskilled in the art to which the disclosure pertains without departingfrom the scope and spirit of the disclosure claimed in the accompanyingclaims. Such modifications should not be individually understood fromthe technical spirit or the prospect of the disclosure.

What is claimed is:
 1. A method of manufacturing a display module, themethod comprising: forming an epitaxial film comprising a light emittinglayer, a first type semiconductor layer, and a second type semiconductorlayer; attaching the epitaxial film onto an intermediate substratecomprising a conductive material; patterning the epitaxial film to forma light emitting diode (LED); and electrically connecting the LED to adriving circuit layer through the conductive material.
 2. The method asclaimed in claim 1, wherein the connecting the LED to the drivingcircuit layer comprises: attaching the intermediate substrate onto thedriving circuit layer formed on a substrate to electrically connect thefirst type semiconductor layer of the LED to the driving circuit layerthrough the conductive material and to electrically connect the secondtype semiconductor layer of the LED to the driving circuit layer throughthe conductive material.
 3. The method as claimed in claim 2, whereinthe LED has a vertical structure, and the conductive material comprisesat least one of carbon nano tube (CNT), graphene, or metal nano wire. 4.The method as claimed in claim 3, wherein the driving circuit layercomprises a pixel circuit, and a first electrode and a second electrodecoupled to the pixel circuit to electrically connect the first electrodeand the second electrode to the pixel circuit.
 5. The method as claimedin claim 4, further comprising forming a passivation element on asidewall of the LED.
 6. The method as claimed in claim 5, wherein theconnecting the second type semiconductor layer of the LED to the drivingcircuit layer comprises: forming a transparent electrode along thepassivation element; and electrically connecting the second typesemiconductor layer of the LED to the second electrode of the drivingcircuit layer through the transparent electrode and the conductivematerial.
 7. The method as claimed in claim 6, further comprisingforming a black matrix on the intermediate substrate in a region betweenthe LED and another LED.
 8. The method as claimed in claim 4, whereinthe intermediate substrate further comprises an adhesive material, andwherein the intermediate substrate is attached onto the driving circuitlayer through the adhesive material to electrically connect the firsttype semiconductor layer of the LED to the first electrode of thedriving circuit layer through the conductive material.
 9. The method asclaimed in claim 8, wherein the adhesive material comprises at least oneof epoxy, polyimide, or phenol.
 10. The method as claimed in claim 2,further comprises forming a reflective electrode on a lower portion ofthe first type semiconductor layer or an upper portion of the secondtype semiconductor layer.
 11. A display module comprising: a substrate;a driving circuit layer provided on the substrate, the driving circuitlayer comprising a pixel circuit and a plurality of electrodesconfigured to be electrically connected to the pixel circuit, whereinthe plurality of electrodes comprise a first electrode and a secondelectrode; an intermediate substrate comprising a first conductiveportion, a second conductive portion and an adhesive portion provided indifferent regions, respectively, the intermediate substrate beingattached onto the driving circuit layer through the adhesive portion;and a light emitting diode (LED) provided on the intermediate substrate,the LED comprises a light emitting layer, and a first type semiconductorlayer and a second type semiconductor layer provided on upper and lowerportions of the light emitting layer, respectively, the first typesemiconductor layer is configured to electrically connect to the firstelectrode through the first conductive portion, and the second typesemiconductor layer is configured to electrically connect to the secondelectrode through the second conductive portion.
 12. The display moduleas claimed in claim 11, wherein the LED has a vertical structure. 13.The display module as claimed in claim 12, further comprising apassivation element provided on a sidewall of the LED.
 14. The displaymodule as claimed in claim 13, wherein the LED further comprises atransparent electrode provided along the passivation element, and thesecond type semiconductor layer is configured to be electricallyconnected to the second electrode through the transparent electrode. 15.The display module as claimed in claim 14, further comprising a blackmatrix provided on the intermediate substrate in a region between theLED and another LED.
 16. The display module as claimed in claim 14,wherein the transparent electrode is a same material as the firstconductive portion and the second conductive portion of the intermediatesubstrate.
 17. The display module as claimed in claim 11, wherein eachof the first conductive portion and the second conductive portioncomprises at least one of carbon nano tube (CNT), graphene, or metalnano wire.
 18. The display module as claimed in claim 11, wherein theadhesive portion comprises at least one of epoxy, polyimide, or phenol.19. The display module as claimed in claim 11, further comprising areflective electrode provided on a lower portion of the first typesemiconductor layer or an upper portion of the second type semiconductorlayer.
 20. A display device comprising: a substrate; a driving circuitlayer provided on the substrate, the driving circuit layer comprising apixel circuit, a first electrode and a second electrode; an intermediatesubstrate comprising a first portion and a second portion having aconductive material, and a third portion having an adhesive material,the intermediate substrate being attached to the driving circuit layerthrough the adhesive material in the third portion; a light emittingdiode (LED) provided on the intermediate substrate and having a lightemitting layer, and a first type semiconductor layer and a second typesemiconductor layer, wherein the first type semiconductor layer iselectrically connectable to the first electrode through the conductivematerial in the first portion, and wherein the second type semiconductorlayer is electrically connectable to the second electrode through theconductive material in the second portion.